From the Helmholtz Association of German Research Centres a clear indication for those “CO2 is plant food” scoffers that the plants don’t care what they think.
Productivity of land plants may be greater than previously thought
Researchers recommend the reworking of global carbon models in Nature
This press release is available in German.
London – The global uptake of carbon by land plants may be up to 45 per cent more than previously thought. This is the conclusion of an international team of scientists, based on the variability of heavy oxygen atoms in the carbon dioxide of the atmosphere driven by the El Niño effect. As the oxygen atoms in carbon dioxide were converted faster than expected during the El Niño years, current estimates for the uptake of carbon by plants are probably too low. These should be corrected upwards, say the researchers in the current issue of the scientific journal NATURE. Instead of 120 petagrams of carbon, the annual global vegetation uptake probably lies between 150 and 175 petagrams of carbon. This value is a kind of gross national product for land plants and indicates how productive the biosphere of the Earth is. The reworking of this so-called global primary productivity would have significant consequences for the coupled carbon cycle-climate model used in climate research to predict future climate change.
Lisa Welp of the Scripps Institution of Oceanography at the University of California in San Diego and her colleagues evaluated the data for the global isotopic composition of the greenhouse gas CO2 over the last 30 years. This analysis indicated regular fluctuations between years and a connection with the El Niño phenomenon in the Pacific. Overall, El Niño years are warmer. They are also characterised by greater precipitation in South America and less intensive monsoons in Southeast Asia.
The researchers found a more rapid recovery of the
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isotopic ratios following the El Niño events than assumed, indicating a shorter conversion time for CO2 in the terrestrial biosphere. On the basis of these data, the authors calculate the so-called global primary productivity (GPP). They now propose correcting this in the global models from 120 to 150-175 petagrams) of carbon annually.
Since 1977 the isotopic ratios in the carbon dioxide of the atmosphere (18O/16O und 13C/12C) have been measured in order to better understand the global carbon cycle, as the exchange processes between the biosphere, the atmosphere and the oceans are reflected in these values. “We assume that the redistribution of moisture and rain in the tropics during El Niño raises the 18O/16O ratio in precipitation and plant water and then signals this to the atmospheric carbon dioxide”, explains Lisa Welp the new approach of the researchers.
“Our atmosphere is a perfect blender. Changes in its levels of trace gases – such as carbon dioxide – reflect the overall release and uptake of trace gases from all sources. So if you measure the carbon exchange of a forest ecosystem, for example, you “only” get the net exchange of all the carbon taken up by the trees for photosynthesis and all the carbon released by the trees and soil “, writes Dr. Matthias Cuntz of the Helmholtz Centre for Environmental Research (UFZ) in his commentary in the same issue of NATURE. The gross-exchange fluxes, such as photosynthesis, are however accessible only with difficulty. “Global estimates therefore depend upon a number of assumptions. This includes, for example, how many of the CO2 molecules entering a plant are actually fixed by photosynthesis. The researchers of Lisa Welp’s team assume that around 43 per cent of all CO2 molecules entering a plant are taken up by the plant. If this were only 34%, the estimate would fall to about 120 billion tons of carbon – that is, to the currently accepted value”, for Matthias Cuntz reason of thought. In his opinion, the new findings do not completely upset the research to date. Nevertheless, they demonstrate an interesting new method for the determination of plant productivity over large areas. In future, the combination of several isotopic methods with conventional measurements represents a promising approach.
The now published study was carried out under the direction of Ralph F. Keeling, a professor of oceanography and the son of the late Charles David Keeling, after whom the so-called Keeling curve was named. This graph shows the concentration of CO2 of the volcano Mauna Loa on Hawaii since the year 1957. In the 1950s the CO2 fraction in the earth’s atmosphere was still around 315 ppm. In 2011, by comparison, it has already increased to 390 ppm. With his measurements Keeling was able to show for the first time that the concentration of the greenhouse gas increases in relation to changing land use and the combustion of fossil fuels. This new study underscores the importance of long-term measurements of the isotope 18O in the carbon dioxide of the atmosphere from the scientific point of view, as this occupies a key position between the carbon cycle and the hydrogen cycle.
Publications:
Lisa R. Welp, Ralph F. Keeling, Harro A. J. Meijer, Alane F. Bollenbacher, Stephen C. Piper, KeiYoshimura, Roger J. Francey, Colin E. Allison & Martin Wahlen (2011): Interannual variability in the oxygen isotopes of atmospheric CO2 driven by El Niño.
29 September 2011, Vol. 477, Nature 579, 579-582. doi:10.1038/nature10421
Matthias Cuntz (2011): A dent in carbon´s gold standard.
29 September 2011, Vol. 477, Nature 579, 547-548.
Links:
CO2- and Isotopic Measurement Program of the Scripps Institution of Oceanography, USA:
http://scrippsco2.ucsd.edu/data/atmospheric_co2.html
Atmospheric Measurement Program of the National Oceanic & Atmospheric Administration, USA:
Cape Grim Baseline Air Pollution Station, Tasmania, Australia:
http://www.csiro.au/places/Cape-Grim.html
El Niño – Southern Oscillation (ENSO):
http://de.wikipedia.org/wiki/El_Ni%C3%B1o
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Here’s an interesting illustration of the effect increased CO2 has on plants, and unlike Mr. Gores’s faked high school physics experiment, you can see this one in time lapse from start to finish as it actually occurred.
@ferdinand meeus Engelbeen says:
It is physically impossible for Law Dome to have a resolution better than 60 years. The differential between the ice age and gas age is at least 30 years…
Ice cores cannot resolve CO2 shifts that occur over time periods less than twice the bubble enclosure time. That is basic Nyquist Sampling Theorem.
At the time the cores were taken, the sealing depth ranged from 66-72 m at an ice age of 40-68 years. None of those cores have the resolution to properly image the MLO instrumental record.
@Gail,
Maybe not…
Executive Summary, Chapter 3 of the IPCC Third Assessment Report, The Carbon Cycle and Atmospheric Carbon Dioxide
There are more details on the temperature dependence (and pressure, salinity, Ph) of CO2 solubility in the oceans deeper in the chapter, and again in the Fourth Assessment Report.
David Middleton says:
September 30, 2011 at 12:50 pm
It is physically impossible for Law Dome to have a resolution better than 60 years. The differential between the ice age and gas age is at least 30 years…
David, the resolution of the ice core CO2 measurements have nothing to do with the IGA (ice – gas age difference). As long as the pores are wide enough, there is free exchange between the air in the atmosphere and in the pores. The deeper one goes, the slower the exchanges are, but at 72 m depth for the Law Dome ice cores the ice is 40 years old, so the diffusion has 40 years the time to mix in and out. At that depth the enclosed air is only 10 years older in average than in the atmosphere.
At Law Dome, the CO2 levels in firn top down were measured. At sealing depth, the CO2 levels in firn and ice were equal, but it costs about 8 years to close all bubbles, so different bubbles may contain air of different average ages, in this case about a decade, with the average at 30 years difference between ice age and gas age.
More info about the diffusion and fractionation of gases in ice cores can be found at:
http://www.pnas.org/content/94/16/8343.full
And more interesting for this discussion, a diffusion model (confirmed by direct measurements in firn) shows that a one-year peak in CO2 for Law Dome diffuses down over time and causes a peak trapped in the sealed ice layer with an amplitude of 10% of the original peak at 11 years:
http://courses.washington.edu/proxies/GHG.pdf
For the high resolution Law Dome cores that means that a peak of 20 ppmv in the atmosphere during one year is measurable in the ice core as an increase of maximum 2 ppmv over a period of 8 years (8-16 years after the atmospheric peak).
None of those cores have the resolution to properly image the MLO instrumental record.
To the contrary, the Law Dome ice cores have an overlap of about 20 years with the direct measurements at the South Pole, with a perfect match for that period, within the accuracy of the measurements (1.2 ppmv – one sigma):
http://www.ferdinand-engelbeen.be/klimaat/klim_img/law_dome_sp_co2.jpg
More about the work of Etheridge e.a. on the Law Dome ice cores, unfortunately behind a paywall:
http://www.agu.org/pubs/crossref/1996/95JD03410.shtml
CodeTech says:
People who profess to be Science Professionals do not understand one of the most fundamental characteristics of life itself.
Life seeks food. Availability of food is the limiting factor of life. Plant life is no different. In fact, plants, unlike animals, can usually live to reproduce at amazing extremes of size… either really small or really, really large.
IIRC the current level of carbon dioxide in the atmosphere is actually towards the low end of what plants can handle.
Which is why ANY scheme to reduce CO2, including dumping crap in the oceans or CO2 scrubbers or, outright dangerous and directly wasteful and harmful: sequestration, is a stupid, stupid thing to do.
There are actually devices to increase carbon dioxide levels in greenhouses. The obvious solution is, instead of using complex scrubbers, feed the exhaust from CO2 producing processes into greenhouses.
Even raising it to 20 times current atmospheric levels is perfectly safe for humans. It dosn’t make sense to claim that current levels are “too high” when they appear to be way below optimal for many plants and way below dangerous to animals. Instead it implies that at times in the past the level is likely to have been considerably higher than at present for organisms to evolve the biochemical mechanisms they have…
Ferdinand Engelbeen
I have two problems with the Ice Core data aside from the disagreement with the stomata data.
1. The grahps show CO2 at or below 180-200ppm. An old paper since removed from the internet stated trees stop growing at 220ppm. Other sources indicate plants run into trouble at 180 to 200 ppm.
2. The diffusion of CO2 through the ice.
http://www.geocraft.com/WVFossils/Reference_Docs/CO2_diffusion_in_polar_ice_2008.pdf
http://robertkernodle.hubpages.com/hub/ICE-Core-CO2-Records-Ancient-Atmospheres-Or-Geophysical-Artifacts
GRAPHS
Wiki: http://upload.wikimedia.org/wikipedia/en/6/63/Co2-temperature-plot.svg
http://joannenova.com.au/globalwarming/graphs/ice-cores/vostok-ice-core-petit-web.gif
http://joannenova.com.au/global-warming/ice-core-graph/
I am also well aware that scientists and lab techs will come up with the “correct” answers as Jaworowski suggests. I have certainly seen enough real life examples after more than thirty years in labs to know that “mavericks” like Jaworowski and Alan Carlin, who consider the truth to be more important than their careers are few and far between. Money trumps ethics especially when you have a family to feed and a mortgage to pay.
Given that most readings of CO2 are land based you quibbles with me about “well mixed” do not hold. Not only do land plants absorb CO2, the ocean water absorbs CO2 as does the plant life it contains you can not ignore that as you do in your explanation. You also have volcanoes, factories, and other point sources of CO2 like the soil. The whole blasted planet with the possible exception of the glaciers is CO2 “active”
@ferdinand meeus,
You can’t recover higher frequencies than you put into the ground. The Nyquist frequency is equivalent to two-times the bubble enclosure period.
David Middleton says:
September 30, 2011 at 6:59 pm
You can’t recover higher frequencies than you put into the ground. The Nyquist frequency is equivalent to two-times the bubble enclosure period.
Agreed, but the bubble enclosure period in the high accumulation Law Dome cores is only 8 years starting at 72 m depth. Thus any continuous change of 16 years above the accuracy limits (1.2 ppmv, 1 sigma) can be detected in the ice core. For the lower accumulation third Law Dome core, the closure period is 21 years, thus any frequency of longer than 40 years would be detected. In the case of the MWP-LIA change, the frequency is ~1000 years, thus no problem to detect the change in CO2 between the MWP and LIA, which was about 6 ppmv. That means that it is highly unlikely that the variability seen in stomata data is real, anyway the higher average CO2 levels are impossible, as the ice core data are filtering out the higher frequencies, but filtering doesn’t change the average…
The confusion, I suppose, is in the ice-gas age distribution, but the diffusion of air/CO2 through the firn until closing depth is independent of the ice age, only depends of temperature and pore diameter/ice density. The closing period also is temperature dependent and accumulation dependent. For the high accumulation, “warm” (-19°C) Law Dome ice cores the closing period is 8 years, but for the very cold (-40°C) low accumulation Vostok and Dome C ice cores, that is 600 and 560 years resp (worse in glacial periods). But even these two would detect the current (one-sided!) increase of 110 ppmv over 1.5 century…
I remember learning this in school like 20+ years ago. First in biology, then in chemistry, where we actually did the photosynthesis calculation. We learned that CO2 is good for plants. Plants love CO2. It’s nom-tastic for them.
How much has changed in 20+ years. It’s actually creepy.
Maybe this helps explain how my bare-root, mail-order tuliptree planted in spring 2004 is now 40′ (>13m) tall! Even w/only 6 hrs direct sun a day. At that rate it could be 100′ in a mere 20 yrs. Chinese elm and honeylocust planted at the same time are only slightly behind in height — over 35′ tall.
Gail Combs says:
September 30, 2011 at 6:28 pm
1. The graphs show CO2 at or below 180-200ppm. An old paper since removed from the internet stated trees stop growing at 220ppm. Other sources indicate plants run into trouble at 180 to 200 ppm.
Land plants have the advantage to grow on… land. CO2 levels in the first few hundred meters in average are elevated (some 30-40 ppmv) compared to “background” CO2 levels. At ground level even up to 1000 ppmv. The “background” represents 95% of the atmosphere, including all heights over the oceans and over barren land like Antarctica. Thus the real CO2 levels over land might have been 210-240 ppmv while the ice cores show 180-200 ppmv.
2. The diffusion of CO2 through the ice.
The investigation of CO2 diffusion is quite difficult, because it is so small. In the case of the Siple Dome, they used CO2 levels in the neighbourhood of impermiable (remelt) layers to estimate the diffusion over longer time. The result for this “warm” (-21°C) ice core is that the resolution at medium depth is broadened from 20 to 22 years and at full depth (70 kyr in the past) from 20 to 40 years. Not really a problem, as there is more averaging, but that doesn’t change the average, only reduces the ability to detect fast changes.
For “cold” (-40°C) ice cores like Vostok and Dome C, the diffusion is unmeasurable small. That is proven by the CO2/temperature ratio which remains the same over 800,000 years, with a warmer period every 100,000 years back in time. If there was the slightest migration, the highest CO2 levels (at 10% of the time) would fade away for each period further back in time.
I am aware of the objections from Jaworowski/Segalstad against the reliability of ice cores. Most of the objections are from 1992 and before and most were answered in 1996 by the work of Etheridge e.a. on the Law Dome ice cores.
Further, Jaworowski claims points which are physically impossible, like migration of CO2 out of the ice core via cracks, while the outside CO2 levels are 100 ppmv higher… See further:
http://www.ferdinand-engelbeen.be/klimaat/jaworowski.html
Even if some ice core specialists would be economical with the truth, it seems very unlikely to me that really nobody of all (tens of) people from different labs and different countries working at different cores in different time periods would protest against such a practice, even not after retirement…
Ferdinand Engelbeen
So average atmospheric CO2 is slighly lower than at ground level? Is this a fig leaf to jusify the suicidally irresponsible policy of reducing CO2 when current atmospheric levels are dangerously near the low, not the high, end of the safe range of 300 – 10,000 ppm evident from palaeo history?
That the biosphere is stressed by current low CO2 is evidenced by the recent evolution 24 MYa of monocotyledonous plants (e.g. grasses) with their more efficient C4 photosynthesis.
BTW grasslands have higher albedo than forests, this could be a factor in the current glaciation as much as any direct physical effect of CO2 on temperature.
Has the movement for voluntary human extinction become influential at government and UN level?
In the paper by Franck et al. on the timeline of biosphere extinctions, he points out that it will be CO2 starvation, not temperature, that will finally kill off all life on this planet within the next billion years.
phlogiston says:
October 1, 2011 at 9:28 pm
Has the movement for voluntary human extinction become influential at government and UN level?
Probably, but I am not very interested in the policy of the UN, except that what they do in the case of CO2 costs a lot of money for little effect.
I am more interested in what the observations show: CO2 levels over land and especially near ground are (much) higher than in the rest of the atmosphere, so that may help the survival of plants when most of the atmosphere is at the 180-200 ppmv level during glacial times. Thus the survival of plants is not an argument against the low levels found in ice cores during such periods.
For plants anyway higher levels are better. And for climate, I would like to have the Mediterranian climate here in my (in general) cool and wet country…
I’m sorry, Ferdinand, but you are totally wrong…
Aa = Ai + δa = Ai + Ts – Td
δa = Ts – Td
Aa = Mean air age
Ai = Ice age at extraction depth
Ts = Time for ice to reach sealing depth
Td = Time for air to mix down to sealing depth
DE08 205
Ai= 1939
Aa= 1969
δa= 30
Ts= 40
Td= 10
d= 72
The bubble enclosure time is 4 times the time for the air to mix down to the sealing depth. Every point in the DE08, DE08-2 and DSS cores is approximately a 30-yr moving average of annual CO2 concentrations. The highest frequency recoverable is equivalent to a 30-yr period. The Nyquist frequency at Law Dome is equivalent to a period of 60-yr.
Law Dome cannot resolve CO2 shifts that occur over periods of less than 60 years. That is an absolute immutable fact.
The deepest Law Dome core, DSS, has a δa=58. Its resolution is 116 years.
It can’t resolve any sub-centennial CO2 shifts.
Ferdinand Engelbeen
Thanks for the reply. Its a good thing for plants that local CO2 is significantly elevated over the atmospheric mean.
Out of interest would the presence of these 2 compartments – ground level (say over a tropical rain forest) and the higher mixed compartment – combined with any measured differences in C isotope ratios in the 2 compartments, provide any handle on CO2 kinetics, e.g. residence time
/ half life? Or is this wishful thinking.
Dave Middleton
If imaging technology is anything to go by, the oft-cited Nyquist frequency is more of a guideline than an immutable law – in the real world higher spatial resolutions are attainable, but only if you get everything right in terms of stability, alignment etc.
For instance resolution as measured by 10% MTF (Fourier modulatuon transfer frequency) often comes in at around
1.5 times, not 2x, the pixel size.
@phlogiston
There are “tricks” to infer better resolution than Nyquist. We can use amplitude and other attributes to infer stratigraphic variability below minimum resolution thickness in reflection seismic profiling for oil exploration; but we don’t have the academic liberty to ignore Nyquist.
David Middleton says:
October 2, 2011 at 6:53 am
David you are confusing between mean gas age of the air enclosed in the ice and gas age distribution within that enclosed air.
At sealing depth of 72 meter, the air is starting to be sealed from the atmosphere. At that moment the average gas age is only 10 years older than in the atmosphere, while the ice age is already 40 years. The gas age distribution at that moment is mainly +/- 3 years, be it with a relative long tail of older gas ages. Then it takes about 8 years to close all bubbles. That means that the average gas age now goes up at the same pace as the ice age, thus the mean gas age now is 18 years and because of less and less sealing bubbles left, the gas age distibution then is less than 8 years + the gas age distribution at sealing start depth, that makes about 11 years for the main age distibution, with relative smaller leads and longer tails of younger and older air, see Fig 11 in:
http://courses.washington.edu/proxies/GHG.pdf
The bubble enclosure time is 4 times the time for the air to mix down to the sealing depth.
Here you are mistaken: there is no bubble enclosure until 72 m depth and all air is fully enclosed at 83 m depth, that is about 8 years (with 1.2 m ice equivalent precipitation at Law Dome). Thus the bubble enclosure time is less than the mix down time of the air in the firn.
The bubble enclosure time and gas age distribution in the bubbles have nothing to do with the mean gas age or ice age or ice age – gas age difference, only with temperature and the static pressure caused by precipitation.
How come that “seeing is believing” video doesn’t take into account nutrient concentration? If there aren’t enough nutrients available (primarily the most limited one, phosphorus) then you won’t see that growth no matter the CO2 concentration.
fsu1jreed says:
October 3, 2011 at 9:44 am
How come that “seeing is believing” video doesn’t take into account nutrient concentration? If there aren’t enough nutrients available (primarily the most limited one, phosphorus) then you won’t see that growth no matter the CO2 concentration.
The experiment was done in optimal conditions, that is with sufficient water, nutritients, fertilizers and the adequate temperature. That gives a huge difference in plant growth with increased CO2 for many plants, but not for all. In average a 50% increase in carbon mass for a CO2 doubling. In the real world, conditions are not always optimal, as there may be insufficient nutritients, sub-optimal temperatures, lack of water, etc…
That makes that the “greening earth” at this moment gives an increase of about 1 GtC more uptake than release (on an estimated 550 GtC living biomass) for a 30% increase in atmospheric CO2 level. Not that much, but anyway positive.
Ferdinand,
You are totally 100% wrong.
The sealing interval is below the bubble enclosure interval. Sintering begins when the snow is buried to a depth sufficient to compact its density to 0.55 kg/l (~9 m at DE08). The bubbles begin to close off at ~.70 kg/l (~60 m at DE08) and are completely sealed off at a density of ~0.84 kg/l (72 m at DE08). At the time the core was drilled (1987), the relatively open mixing interval was from the surface down to ~60 m (“1954” ice layer). The sealing interval was from 60-72 m (1954 down to 1946). Even though the sealing interval only spanned 8 ice years, it contained a 30-yr blend of gases because it took that interval ~30 years to be buried to a depth sufficient to achieve sealing density.
At the time of deposition of the “1969” ice layer in the DE-08 core, the top of sealed ice was at an approximate depth of 72 m at the “1929” layer. The sealing interval in 1969 was from the “1937” layer down to the “1929” layer. From the 1969 surface down to the “1937” layer the firn was permeable. During the 10 years that the 1969 air mixed down to the “1939” layer, the 1929-1937 interval sealed completely off.
The air trapped at the “1939” ice layer was a mixture of 1939-1969 air. The mean age of that air was not 1969, as asserted by Etheridge et al.; the mean air age was no younger than 1954. It was actually older than 1954 because the firn/ice becomes less permeable with depth.
Once again, it is physically impossible for the DE08 or DE08-2 cores to resolve CO2 shifts that occur over periods of less than 60 years; and it is impossible for the DSS core to resolve CO2 shifts of shorter duration than 116 years. Below 120 m in the DSS core, the resolution may actually even be much worse than 116 years. There is a pronounce decline in the sampling rate below 120 m. There is a linear decline from 0.74 m/yr to 0.27 m/yr from 116.9 m down to 523.6 m.
The linear nature of the trend means that this is most likely due to compaction, rather than accumulation rate. If the sampling rate decline is due to compaction, it would only have a minimal effect on resolution. If it’s due to accumulation rate, then the resolution below 120 m could be as poor as ~500 years.
David Middleton says:
October 5, 2011 at 6:58 am
David,
Sorry for the late reply, didn’t check this discussion again until know…
Again you are mixing the average gas age and the distribution of the age in the bubbles. Indeed it takes 40 years until closing depth, but because the still open connection with the atmosphere, the average age of the air at that moment is 10 years older than in the atmosphere, not 20 years. Even if for slower accumulating ice cores, the ice age was already 500 years at closing depth, that wouldn’t change the average gas age much from the 10 years, as mean gas age and ice age are independent of each other (only temperature plays some role for both). 80% of the gas mixture is 5-15 years old in both cases, 10% is younger and 10% is older, where the older part has a very long tail up to 40 years (or 500 years for other cores).
The mean air age of the DE08 core was calculated from a firn densification model and confirmed by direct measurements of CO2 levels in the firn: because there is an overlap of 20 years between direct measurements at the South Pole and in the firn and there is a trend in the atmospheric CO2 levels, we know the average age of the gas mixture in the firn. Other items (CH4, bomb 14CO2, CFC’s) did confirm that. Thus the average gas age at the “1939″ ice layer was a mixture of 1939-1979 (not 1969) air and the mean age of that air was certainly at 1969, because that is what was measured. The mixture of gas ages is not a normal Gaussian distribution, it is quite assymetric, as fig. 11 in http://courses.washington.edu/proxies/GHG.pdf shows.
So you are right that the DE08 mixture has a distribution of air over a period of 40 years, but most of the air is in the +/- 5 years range around the mean gas age. The total distribution is not relevant to detect any peak in CO2 levels for a short or longer period, because the values around the average gas age have enough amplitude to detect any change of 20 ppmv over one year or 2 ppmv sustained over 20 years. That is much sharper than what you expect from a Gaussian distribution.
Even a sinusoidal CO2 level variation with a wavelength of 20 years and an amplitude of 20 ppmv would be detected in the DE08 core of Law Dome. That is by far sharp enough to reject the high(er) amplitudes seen in stomata data or the 1942 “peak” from historical CO2 measurements by wet chemical methods. And sharp enough to know from the DSS core that the LIA had CO2 levels at some 6 ppmv lower than during the MWP. Or sharp enough to detect a 100 ppmv increase over 100 years, like we have nowadays, in the Vostok or Dome C ice cores in the 800 kyr past.